Cooling unit for a selective cooling of casting piece as they are obtained in casting molds

ABSTRACT

cooling unit for use in sand molds where casting parts are obtained. The coolers consist of several modules ( 5 ) mounted on a support ( 4 ) with a certain clearance, and attached to it by a bar ( 7 ), being placed on a pallet ( 3 ) handled by robotic means and displaceable within a casting installation together with an upper pallet ( 1 ) in which the mold is placed, which is superimposed and coupled on the lower pallet ( 3 ) in the automated assembly of the mold on the cooling unit, the mold being automatically disassembled from the cooling unit after the cast part (P) is obtained. Each cooler module ( 5 ) can consist of a single part, two parts ( 5′ ) or three parts ( 5″ ), and it is mounted on the corresponding support ( 4 ) with a clearance ( 6 ) in order to absorb the expansions and contraction caused by the heat transmitted by the molten metal.

OBJECT OF THE INVENTION

[0001] The present invention relates to a cooling unit used in sand casting molds to cool certain areas of the casting piece obtained in these molds.

[0002] The object of the invention is to incorporate in the cooling unit a series of cooling modules meant for use in the molding stage of, for example, engine blocks obtained by melting aluminium in sand molds, in order to obtain improved metallurgical properties of certain areas of the piece obtained.

[0003] A further object of the invention is that the cooling unit incorporates a support of the cooling modules, coupled to a pallet, which defines the base for its motion in an automated casting installation where the sand casting mold is inserted in the cooling unit, the assembly is displaced towards the casting station where the molten metal is poured on the sand mold, there is a subsequent cooling by the cooling unit and the sand mold and cast part are extracted from the cooling unit.

[0004] Also the object of the invention are the extraction means used to remove the sand mold from the cooling unit after the casting part is obtained with a selective cooling.

BACKGROUND OF THE INVENTION

[0005] In processes for casting aluminium pieces, such as certain engine blocks, coolers are known that are disposed on certain areas of the casting mould for the purpose cooling the poured aluminium more quickly in the zone in contact with the cooler, thereby improving the metallurgical properties of the piece in the areas that have cooled more quickly.

[0006] In casting of aluminium engine blocks, coolers are known to be used for a faster cooling of the parts of the piece that will constitute the crankshaft seat, the coolers being built based on a cylindrical cast iron body that is placed in the mould before the metal is poured, so that the cylindrical body causes a faster cooling in the partitions that will conform the crankshaft seat.

[0007] In accordance with the method hitherto employed, the cooler only acts on the surface of the piece that is in contact with it, so that its effectiveness is limited in practice to one side of the piece.

[0008] In a production line for aluminium engine blocks, the basic operative sequences are the following:

[0009] Firstly, the cores are placed inside the sand mould, followed by the coolers, the latter being positioned and secured in the most suitable manner. Subsequently, the metal is poured into the mould, which passes into the cooling station and then to the de-moulding station.

[0010] The casting can be de-moulded by vibration, although it is currently achieved by a heat treatment that melts the binder resin, loosening the sand and destroying of the mould in a simple manner, all of this such that after the mould is destroyed the casting is obtained, continuing along its path to receive the required treatments; in addition, the sand is obtained joined to the coolers. This sand must be separated from the coolers before it is returned to the recovery plant. This separation is generally achieved by vibration. Tho operation of separating the sand from the coolers requires time and appropriate means, resulting in an additional economic cost.

[0011] In view of these operative sequences, destruction of the mould by means of heat treatment implies heating the coolers, so that the energy efficiency is reduced.

[0012] In addition to these drawbacks must be added the fact that in the traditional system the number of coolers required is very high.

DESCRIPTION OF THE INVENTION

[0013] The cooling unit for casting pieces object of the invention is meant to solve the problems described above, providing an independent assembly that is controlled by robotic means and which can move in a casting installation. The cooling unit is mainly characterised in that a sand mold is mounted above it where the molten metal is cast. This mold is extracted from the cooling unit after a selective cooling of the casting part with the cooler and the final casting part is obtained.

[0014] It should be remarked that unlike other cooling systems where the cooler is inserted in the sand mold, the cooling unit object of this invention proposes that the cooling unit be an independent assembly on which the sand mold is inserted and extracted, and which with the sand mold assembled on the coolers allows the assembly to move on the base supporting the cooling unit and not on the base supporting the mold.

[0015] The cooling unit consists of a series of cooling modules integrated on a support, to which they are coupled by a bar or the like, which support is in turn mounted on a pallet so that the assembly thus obtained can be easily handled.

[0016] Each cooling module consists of one, two or three parts, so that if the module consists of two or more parts these are mounted with a clearance between them in order to absorb any expansion or contraction resulting from the temperature changes which take place during the heating and cooling stages. These clearances also determine escape paths for the air when pouring the molten metal, thereby facilitating the filling operation of the mold, even at the corners or complicated points.

[0017] Likewise, the cooling nodules are also mounted with a certain clearance on the support, in order to absorb any expansions or contractions.

[0018] The cooling modules are designed so that the partially embrace the molten part, so that these are in contact not only on the front of one face but also on part of the sides, achieving cooling of the front and sides of the molten part.

[0019] Below is described the process followed in a casting installation using the cooling units object of this invention in a fully automated manner.

[0020] On one side, the cooling unit is directed towards an assembly station arriving from a closed circuit where on the order of one-hundred and fifty cooling units are moved continuously, and on the other the sand molds arrive from an feeder line and are directed towards the said station.

[0021] At the assembly station the sand mold is incorporated on the cooling unit, and the assembly thus obtained is then directed towards a casting station where the molten metal is poured on the sand mold.

[0022] The assembly then proceeds along a cooling line until reaching a disassembly station, where the mold is extracted together with the molten part from the cooling unit with the extraction means described in the following paragraph, the mold and the part being send towards an outlet line where the mold the part are separated. The cooling unit is sent to a return line, which later continues as a treatment line for cleaning and painting, among other operations, and then towards the assembly station for a subsequent use with another mold to begin a new cycle.

[0023] The extraction means used to separate the mold and the casting part from the cooling unit essentially consist of a table moved vertically by a hydraulic cylinder, the table being provided with lower guides and four upper stems which cross corresponding orifices established in the pallet of the cooling unit, the stems reaching the base of the mold to raise it and separate it from the cooling unit.

[0024] Among the advantages provided by the system of coolers disclosed can be mentioned the following:

[0025] It improves the energy efficiency of the casting treatment system.

[0026] It solves the problem of separating the piece-cooler-sand in the return circuit of the casting line.

[0027] It allows controlling the process followed by the cooler itself, eliminating vibrations, knocks, etc.

[0028] It facilitates control in the reference change in production.

DESCRIPTION OF THE DRAWINGS

[0029] As a complement of the description being made and in order to aid a better understanding of the characteristics of the invention, according to a preferred embodiment, a set of drawings is provided as an integral part of the description where for purposes of illustration only and in a non-limiting sense the following is shown:

[0030]FIG. 1 shows a longitudinal section of a sand mold and its components, mounted on the cooling unit object of the invention, as well as the casting part to be cooled.

[0031]FIG. 2 shows a cross section of the assembly of the previous figure.

[0032]FIG. 3 shows a detailed view of the assembly of the cooling modules on the support, coupled to it and to each other by means of a transverse bar, showing a cooling unit having a single part, another module consisting of two parts and a third module having three parts, in all cases showing the corresponding clearances.

[0033]FIG. 4 shows a schematic representation of the casting installation showing the path followed by the cooling unit with a double arrow and the path followed by the mold with a solid arrow.

[0034]FIG. 5 shows a section view of a specific embodiment of the cooling unit.

[0035]FIG. 6 shows a front view revealing the assembly formed by the mold-molten part, the cooling unit and the extraction means used to separate the mold-molten part assembly from the cooling unit in the rising stage of said extraction means.

[0036]FIG. 7 shows a front view of the elements described in the previous figure, revealing the mold-molten part assembly in a raised position and separated from the cooling unit by the action of the extraction means.

PREFERRED EMBODIMENT OF THE INVENTION

[0037] In view of the described figures, the cooling unit for casting parts can be seen to be characterised by having cooling modules (5) mounted on a support (4) to which they are coupled by a bar (7) that crosses all the cooling modules (5), said support (4) being mounted on a lower pallet (3) handled by robotic means and displaceable within the casting installation, as well as an upper pallet (1) where the mold is provided, which is superimposed and attached on the lower pallet (3) during the automated assembly of the mold on the cooling unit, the mold being automatically disassembled from the cooling unit after the casting part (P) is obtained.

[0038] The sand mold comprises the lid or upper core (17), the base or lower core (18) and the set of cores (19), and it is connected to an upper pallet (1) by the keys (2).

[0039] The upper pallet (1) supporting the sand mold is provided with a wide central opening (29) with a shape and size matching that of the perimeter of the cooling unit support (4) to facilitate the introduction of the sand mold on the cooling unit.

[0040] On the support (4) are placed the cooling modules (5), which can consist of a single part, two parts (5′) or three parts (5″), as shown in FIG. 3.

[0041] The cooling modules (5) are provided with a recess so that the casting part (P) is cooled not only on its front face but also on its sides, as show in said FIG. 3.

[0042] Between the cooling modules (5) and the support (4), as well as between the parts (5′-5″) forming a single module there is a clearance (6-6′), respectively, means to absorb any expansions and contractions, as well as to allow escape of air contained in the mold when melting the part.

[0043] It is possible to affirm that the independent nature of the cooling unit facilitates the process taking place in the casting installation. Described in what follows are the various stages of assembly and disassembly of the mold with respect to the coolers in an automated casting installation.

[0044] The cooling units are carried by their pallets (3) in a motorised line, following a closed circuit which includes a return line (13), a treatment line (16) for painting and cleaning among other operations, an assembly station (14) followed by a cooling line (10) until reaching the disassembly station (11) which connects with the aforementioned return line (13).

[0045] In addition, the sand molds are carried mounted on the upper pallets (1) on a feeder line (15) to the assembly station (14). A handler (not shown) is placed at this station to introduce the mold on the cooling unit so that the upper pallet (1) rest on the lower pallet (3) of the coolers.

[0046] Then the assembly formed by the mold and the cooling unit is moved by a displacement of the lower pallet (3) of said cooling unit until reaching the casting station (8) where the molten metal is poured inside the mold.

[0047] After this the above described assembly travels along the cooling line (10) until reaching the disassembly station (11) where extraction means (20) are provided to raise the mold with its upper pallet (1) and detach it from the cooling unit, as well as a robotic handler (not shown) which carries the upper pallet (1) with the mold and the cast part (P) inside it to an outlet line (12) where the cast part (P) is disassembled from the mold.

[0048] In addition, the cooling units are sent to the return line (13) to be taken to the treatment line (16) and later to the assembly station (14) for use in a subsequent cycle with another mold.

[0049] With the use of this type of cooling units it is possible to obtain a fully automated continuous process in casting installations, thereby allowing to feed the entire installation with a small number of cooling units, on the order of 40 or 50; this is important due to the high cost and maintenance of cooling units.

[0050]FIGS. 6 and 7 show the extraction means (20) of the mold from the cooling unit, fundamentally consisting of a table (21) vertically displaceable by action of a hydraulic cylinder (22) whose stem acts on the lower face of the table (21), also provided with vertical guides (23) to guide the table (21) with respect to a fixed frame (28) placed in the disassembly station (11), the table (21) also having on its face stems (24) that rise together with the table (21) and cross orifices (25) made in the lower pallet (3) of the cooler until pushing the lower face of the upper pallet (1) which carries the mold, raising the upper pallet (3) and the mold until releasing them from the cooling unit.

[0051] In order to ensure that the lower pallet (3) is still during the push of the stems (24), it is retained by anchorings (26) joined to the frame (28), to which are connected the hydraulic cylinder (22) and wheels (27) on which rests the lower pallet (3). 

1.- Cooling unit for selective cooling of casting parts when they are obtained in casting molds made of sand, especially applicable in processes for casting aluminium parts such as engine blocks, essentially characterised in that it comprises cooling modules (5) mounted on a support (4) to which they are joined by a bar (7) which crosses all the cooling modules (5), with this support (4) being mounted on a lower pallet (3) handled by robotic means and displaceable within a casting installation together with an upper pallet (1) on which the mold is placed, which is superimposed and attached to the lower pallet (3) during the automated assembly of the mold on the cooling unit, the mold also being automatically disassembled from the cooling unit after obtaining the cast part (P). 2.- Cooling unit for selective cooling of casting parts when they are obtained in casting molds according to claim 1, characterised in that the cooling module (5) is mounted on the support (4) with clearances (6) to absorb the expansions and contractions caused by the heat transmitted by the molten metal. 3.- Cooling unit for selective cooling of casting parts when they are obtained in casting molds according to claim 1, characterised in that the cooling module (5) consists of a single part. 4.- Cooling unit for selective cooling of casting parts when they are obtained in casting molds according to claim 1, characterised in that the cooling module (5) consists of two parts (5′) with a clearance (6′) between them defining escape paths for the air when pouring the molten metal. 5.- Cooling unit for selective cooling of casting parts when they are obtained in casting molds according to claim 1, characterised in that the cooling module (5) consists of three parts (5″), with a clearance (6′) between them defining escape paths for the air when pouring the molten metal. 6.- Cooling unit for selective cooling of casting parts when they are obtained in casting molds according to claim 1, characterised in that the cooling modules (5) embrace the cast part (P) on its front and side faces in order to cool them. 7.- Cooling unit for selective cooling of casting parts when they are obtained in casting molds according to claim 1, characterised in that the upper pallet (1) supporting the sand mold is provided with a large central opening (29) with a size and shape matching the perimeter of the cooling unit support (4) in order to facilitate the insertion of the sand mold in the cooling unit. 8.- Cooling unit for selective cooling of casting parts when they are obtained in casting molds according to claim 1, characterised in that it incorporates extraction means (20) for the mold from the cooling unit consisting of a table (21) vertically displaceable by action of a hydraulic cylinder (22) whose stem acts on the lower face of the table (21), which is also provided with vertical guides (23) to guide the table (21) with respect to a fixed frame (28) placed in the disassembly station (11), the table (21) also having on its top face stems (24) that rise together with the table (21) and cross orifices (25) made in the lower pallet (3) of the cooler until pushing on the lower face of the upper pallet (1) which carries the mold, raising the upper pallet (1) and the mold until releasing them from the cooling unit, with the hydraulic cylinder (22) being mounted on the fixed frame (28), which is also provided with anchorings (26) for retaining the lower pallet (3) while raising the upper pallet (1) and wheels (27) on which rests the lower pallet (3). 